Influence of soil moisture on egg cold hardiness in the migratory locust Locusta migratoria (Orthoptera: Acridiidae)

Authors

  • XIAN-LEI QI,

    1. 1 State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China and 2College of Plant Protection, Shandong Agricultural University, Tai-an, China
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    • *

      These authors contributed equally to this work.

  • 1,2 XIAN-HUI WANG,

    1. 1 State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China and 2College of Plant Protection, Shandong Agricultural University, Tai-an, China
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    • *

      These authors contributed equally to this work.

  • 1 HONG-FU XU,

    1. 1 State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China and 2College of Plant Protection, Shandong Agricultural University, Tai-an, China
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  • and 2 LE KANG 1

    Corresponding author
    1. 1 State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China and 2College of Plant Protection, Shandong Agricultural University, Tai-an, China
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Dr Le Kang, Institute of Zoology, Chinese Academy of Sciences, 25 BeiXisihuan Road, Haidian, Beijing, China, 100080. Tel.: +86 10 62554979; fax: +86 10 62565689; e-mail: lkang@ioz.ac.cn

Abstract

Abstract The present study investigates the influence of environmental moisture on cold hardiness of the migratory locust, Locusta migratoria. The water content of locust eggs kept in soil at 30 °C varies according to the moisture content of the substrate. In turn, it can significantly affect the supercooling point of locust eggs (range from −26 to −14.8 °C) and the mortality when exposed to subzero temperatures. Environmental moisture influences the supercooling capacity of eggs and their survival at low temperature. When locust eggs of the same water content are exposed to subzero temperatures under different soil moistures, their mortality varies between short-time exposure and long-time exposure at subzero temperatures. Given a short-time exposure, mortality in wet soil is lower than in dry soil due to the buffering effect of soil water against temperature change. The pattern of egg mortality is reversed after long-time exposure at low temperature, suggesting that inoculative freezing may be an important mortality factor. It is suggested that interactions between soil moisture and low temperature can influence the cold hardiness of locust eggs, and partial dehydration is beneficial to over-wintering eggs of the migratory locust.

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